Elastic support for the light source of a scanner

ABSTRACT

In the scanning optical module of a scanner, the light source module is mounted over the lens module through a spring to push the light source module against the scan window. Thus, the light source is moved closer to the document to be scanned and irradiates the document with higher intensity than prior art light source, which must be clear away from the scan window to allow for manufacturing tolerances.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a scanner, in particular to the light sourceof the scanner.

(2) Description of the Related Art

In the optical system of a scanner, the light source module can besubdivided into a “light source module” and a “lens module”. The lightsource module refers to the light source components including the lightsource and the base for supporting the light source. The lens module isto process the light ray with imaging signal including reflectingmirrors and focusing lens, etc. Conventional light source module andlens module are fixed with respect with each other.

FIG. 1 shows the top view of a typical optical module. The light 16 ismounted on an L-shaped base 12 by means of two bracelets 18 as shown inFIG. 2, which is the side view of FIG. 1. The L-shaped base 12 ismounted over the lens module 10. The light source scans and irradiatesdocument 50 placed over a scan window 20 and produces a reflected lightray to pass through the light slot 14 on the lens module 10. As shown inFIG. 2, the reflected light ray 22 through the light slot 14 containsimage signal and is reflected by the mirror 102 for further signalprocessing.

The L-shaped base 12 has a vertical flange. While the flange canreinforce the base to prevent bending and concentrate the lightintensity to prevent scattering, the vertical flange protrudes upwardtoward the scan window 20 typically to an elevation higher than thebrackets 18 as shown in FIG. 2. Due to manufacturing variations,allowance must be made to tolerate the any variations in the dimensionsof the different components in the light source module and the lensmodule. In a practical design, the highest point in the light sourcemodule must clear the bottom of the window 20 by 3 mm. Otherwise, whenthe optical module scans the document back and forth, the top of theL-shaped base 12 may scratch the bottom of the scan window and theoptical module may even be blocked. As shown in FIG. 2, the distance 66is the minimum distance of 3 mm allowed for variations in mechanicaldimensions of the different components. In practical scanners, the 3 mmallowance is barely enough to prevent scratching.

Such an allowance is not desirable, because the light source 16 must bemoved away from the scanned document and is weakened as it irradiatesthe document.

SUMMARY OF THE INVENTION

An object of this invention is to irradiate the scanned document with amore intense light. Another object of this invention is to move thelight source closer to the document being scanned. Still another objectof the present invention is to provide smoother scanning motion for theoptical module.

These objects are achieved by mounting the light source module over thelens module through a spring. The spring pushes the light source moduleagainst scan window with minimum clearance. Thus, the light source ismoved closer to the document being scanned and the intensity isincreased.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows the top view of a prior art light source module.

FIG. 2 shows side view of FIG. 1.

FIG. 3 shows the side view of a first embodiment of the presentinvention.

FIG. 4 shows an enlarged view of FIG. 3.

FIG. 5 shows the side view of a second embodiment of the presentinvention.

FIG. 6 shows the side view of a third embodiment of the presentinvention.

FIG. 7 shows the side view of a fourth embodiment of the presentinvention.

FIG. 8 shows the side view of a fifth embodiment of the presentinvention.

FIG. 9 shows the end view of FIG. 8.

FIG. 10 shows the side view of a sixth embodiment of the presentinvention.

FIG. 11 shows a first design of the sliding guide for the light source.

FIG. 12 shows a second design of the sliding guide for the light source.

FIG. 13 shows a third design of the sliding guide for the light source.

FIG. 14 shows the end view of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows the side view of the first embodiment of the presentinvention. The light source 16 is held by the brackets 38, which aremounted on an L-shaped base 12. The upper tip of the vertical flange ofthe L-shaped base is lower than the upper tips of the brackets 38. TheL-shaped base is coupled to the optical module 10 through a spring 30,which pushes the tips of the brackets 38 against the bottom of the scanwindow 20, over which a document 50 to be scanned is placed. The bottomof the base 12 and the top of the lens module 10 is separated by adistance 68. Due to intimate contact between the brackets 38 and thescan window 20, the distance between the light source 16 and thedocument 50 is made much shorter than the prior art shown in FIG. 1.Without allowing for manufacturing tolerance, the light source 16irradiates the document with much higher intensity than the prior art.

FIG. 4 shows an enlarged view of the L-shaped base 12 and the spring 30.To provide smooth gliding motion of the light source module under thescan window 20, the brackets 38 can be made of low friction materialsuch as nylon.

FIG. 5 shows a second embodiment of the present invention. The structureis similar to FIG. 4 with same reference numbers referring to the samecorresponding parts. The exception is that only the top 382 of thebrackets 38 is composed of low friction material. The lower section ofthe brackets 38 need not be of low friction material.

FIG. 6 shows a third embodiment of the present invention. The brackets68 for holding the light source 16 are of inverted U-shape. The tops 682of the brackets 68 are in contact with the bottom of the scan window 20.The brackets 68 are made of low friction material to allow smoothgliding motion of the light source 16 under the scan window 20. Thelight source 16 is held by the brackets 68 and mounted on the L-shapedbase 12, which is pushed by a spring 30 as described before.

FIG. 7 shows a fourth embodiment of the present invention. The structureis similar to FIG. 6 with same reference numerals referring to the samecorresponding parts. The exception is that the inverted U-shapedbrackets 68 is capped with a low friction layer 782, and the body of thebrackets 68 itself need not of low friction material. The low frictioncap allows smooth gliding motion of the light source under the scanwindow 20.

FIG. 8 shows a fifth embodiment of the present invention. Two tracks 182of low friction material are attached under the scan window 20. Thesetracks are aligned with the brackets 18 for holding the light source 16.The brackets 18 are similar to those described in FIG. 2 and mounted onan L-shaped base 12, which is pushed by springs 30 against the lensmodule 10. The low friction tracks allows smooth scanning motion of thelight source 16, while maintaining a short distance between the lightsource and the scan window 20.

FIG. 9 shows the side view of FIG. 8. Note the long strip 182 attachedunder the scan window 20.

FIG. 10 shows a sixth embodiment of the present invention. Thisstructure combines the features of FIG. 8 and FIG. 6. The brackets 68have an inverted U-shape and glide under two long tracks 182 under thescan window 20. Here the brackets 68 need not be of low frictionmaterial since the tracks 182 provide the smoothing scan of the lightsource 16. The slight source module base 12 on which the brackets 68 aremounted is pushed by the spring to glide smoothly under the scan window20.

FIG. 11 shows a design of the brackets 78 for holding the light source.The brackets are of U-shape each with two flanges. Each flange is pushedupward by a spring 30.

FIG. 12 shows a second design of the brackets 88 for holding the lightsource. The brackets are of U-shape with a cover 88 wider than theU-shaped groove forming two flanges. The two flanges are pushed upwardby two springs 30.

FIG. 13 shows a third design of the brackets 98. The brackets 98 arecoated directly on the light source 16 and attached to the base 12 ofthe light source module, which is pushed upward by a spring 30. Thecoating may be applied by painting, electrolysis or wrapping.

FIG. 14 shows the end view of FIG. 13. The distance between the lightsource 16 and the window 20 is the thickness of the coating 98.

In prior art, a typical window 20 has a thickness of 3 mm. A typicalallowance 66 between the top of light source module and the scan window20 is 3 mm. In this present invention, the distance between the top ofthe light source module and the scan window 20 is less than 0.2 mm. Thelight intensity is inversely proportional to the square of the distancebetween the light source and the object. In the former case, theintensity is proportional to 1/(3+3)²={fraction (1/36)}, while in thelatter case the light intensity is proportional to 1/(3+0.2)²={fraction(1/10.24)} The light intensity for the present invention is therefore({fraction (1/10.24)})/({fraction (1/36)})=3.52 times stronger thanprior art. Thus, the present intensity ally utilizes the light source.Due to increased intensity the exposure time can be reduced and the scanspeed can be increased. Besides, due the intimate contact between thelight source module and scan window, the structure can tolerate a largevariation in the dimensions of the different components in the lightsource module. The low friction contact material allows smooth scanningmother of the light source module.

While a spiral spring 30 is shown in the foregoing figures, other kindsof springs such as elastic belts may also be used, so long as they canexert a push-up action from the lens module to the light source module.

While particular embodiments of the invention have been described, itwill be apparent to those skilled in the art that various modificationsmay be made without departing from the spirit of the present invention.Such modifications are all within the scope of this invention.

What is claimed is:
 1. An optical module for a scanner having a scanwindow on which a document to be scanned is placed, comprising: a lensmodule comprising reflecting mirrors and focusing lens; an light sourcemodule above said lens module comprising: a light source, a pair ofbrackets for holding said light source, a base for mounting saidbrackets; and elastic means for pushing said light source module againstsaid scan window such that the distance between said light source andsaid scan window is minimized.
 2. An optical module as described inclaim 1, wherein said elastic means comprises at least a spring.
 3. Anoptical module as described in claim 2, wherein said spring is a spiralspring.
 4. An optical module as described in claim 1, wherein said baseis L-shaped with a vertical flange.
 5. An optical module as described inclaim 1, where said brackets are two vertical walls sandwiching saidlight source.
 6. An optical module as described in claim 5, wherein saidbrackets are made of low friction material.
 7. An optical module asdescribed in claim 5, wherein said walls are capped with low frictionmaterial.
 8. An optical module as described in claim 1, wherein saidbrackets have an inverted U-shape, straddling said light source.
 9. Anoptical module as described in claim 8, wherein said brackets are cappedwith low friction material.
 10. An optical module as described in claim1, further comprising two tracks of low friction material attached tothe bottom of said scan window for said brackets to glide on.
 11. Anoptical module as described in claim 10, wherein said brackets eachcomprises two walls sandwiching said light source.
 12. An optical moduleas described in claim 10, wherein said brackets are of inverted U-shape,straddling said light source.
 13. An optical module as described inclaim 1, wherein said brackets are of U-shape with two side horizontalflanges which are pushed upward by two springs from the lens module. 14.An optical module as described in claim 1, wherein said brackets are ofU-shaped and capped by a cover with two overhanging wings which arepushed upward by two springs.
 15. An optical module as described inclaim 1, wherein said brackets wraps around said light source.
 16. Anoptical module as described in claim 15, wherein said brackets areformed by a process selected from the group consisting of painting,electrolysis and wrapping.